We propose a defined research effort on aspects of computer control of therapy machines to improve the delivery of radiation therapy treatment of cancer. It is proposed to develop and test efficient computer programs in order to automate (1) manual procedures in the delivery of treatment (2) record keeping of actual treatment details and (3) moving beam treatments to provide better geometric dose distribution not otherwise possible. The programs will be used on the AECL theratron 80 Teletherapy unit and PDP-11/20 now installed in the Tufts-New England Medical Center. The proposed work will be useful at other installations not only through applications of the programs but even more through the development of program concepts. Method: We will investigate and find solutions to some of the fundamental problems of efficient control of therapy machines and detection and avoidance of collisions. The program will be an extension of our programs for collision detection developed over the previous years as ad hoc, interim solutions. The existing programs will be refined and concepts for collision avoidance developed to produce a final practical set of programs. Detection and avoidance capability will then be applied to develop system concepts and capability for moving beam treatments. Departments of Engineering Design and Radiation Therapy will collaborate in the research.